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Patra S.,Koneru Lakshmaiah University
International Journal of Applied Engineering Research | Year: 2015

MANET is a wireless network connected using movable devices with unstable topology. Unlike MANETS, in a network with static topology, one can estimate and detect the cause for any disturbance in the network. The dynamic topologies in a MANET and the absence of central supervision make the transmission completely prone to several hits. The Mobile Adhoc network is wireless, very adaptive and supports the nodes to travel. This feature is a major support in many applications, but generates many security flaws. This paper discusses various terms related to security in an alphabetical order and references are stated to deal with the each attack. This may serve as a mini dictionary for attacks in Mobile Adhoc networks. © Research India Publications.

Ramakrishna M.,Hindu College | Rao N.,Hindu College | Prasad P.V.D.,Hindu College | Pisipati V.G.K.M.,Koneru Lakshmaiah University
Molecular Crystals and Liquid Crystals | Year: 2010

Alkoxy benzoic acids are well-known liquid-crystalline compounds with nematic phase of long thermal ranges. The refractive indices measurements are carried out using a wedge-shaped cell with the help of a modified spectrometer. The birefringence (δn=ne-no) is obtained directly by using the method developed by Kuczynski et al. [10] in all the available compounds (alkoxy chain number n=3 to 12 and 16). The higher homologues exhibit the smectic-C phase along the nematic phase. The molecular polarizabilities are calculated from the refractive indices and the density using the well-known internal field models. The molecular anisotropy is estimated from the Lippincott -function model and molecular vibration method. The order parameter, S, is estimated (a) using molecular polarizabilities and the molecular anisotropy for both the models, (b) from Haller's extrapolation using molecular polarizabilities, and (c) directly from the birefringence, a method developed by Kuczynski et al. [10] along with the nematic phase. Further, the order parameter from n, without the consideration of any internal field model, to the nematic molecule is compared with S obtained from density due to Maier et al. [23]. The results are compared with one another and the advantages and disadvantages are discussed. Copyright © Taylor & Francis Group, LLC.

Uma G.,National Central University | Uma G.,Koneru Lakshmaiah University | Liu J.Y.,National Central University | Chen S.P.,National Central University | And 3 more authors.
Earth, Planets and Space | Year: 2012

The latest version of the International Reference Ionosphere (IRI-2007) model includes an option for spread-F occurrence prediction for the first-time. The IRI-2007 spread-F occurrence is a function of solar 10.7 cm radiation flux, F10.7. In this paper, an attempt is made to cross-examine the spread-F occurrence derived by the IRI-2007 and the ionospheric scintillations in terms of the maximum value of the S4 index (S4max) between 150-350-km altitudes, calculated from fluctuations of the signal-to-noise ratio (SNR) intensity in the L1 channel of GPS radio occultation signals using FORMOSAT-3/COSMIC (F3/C) satellites during the low solar activity years 2007-2009. It is found that S4max maintains a fairly good consistency with spread-F occurrence simulated by IRI-2007 in the Brazilian region. Thus, the global S4 index statistics can be considered as a viable source of database to be incorporated into the global IRI spread-F prediction scheme owing to fact that the F3/C satellites can provide an unprecedented global database including the S4 index. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS).

Raghunath S.,G Narayanamma Institute Of Technology And Science | Venkata Ratnam D.,Koneru Lakshmaiah University
Indian Journal of Radio and Space Physics | Year: 2016

Standalone Global Navigation Satellite System (GNSS) is inadequate for precise navigation of aircrafts. Ground-based Augmentation System (GBAS) augments the performance of GNSS for civil aviation by providing differential corrections to the position of an aircraft during takeoff and landing. Ionospheric gradients affect the accuracy of GNSS and they can be detected and characterized from GNSS observations. In this paper, the ionospheric temporal and spatial gradients have been detected and the ionospheric drift velocity has been evaluated from the data recorded by GNSS receivers located at Koneru Lakshmaiah University, Guntur (GNT) and Indian Meteorological Department, Machilipatnam (MPM), Andhra Pradesh, India. Both the stations are chosen as they are situated close to each other and to the Vijayawada Airport. The rate of TEC index (ROTI) and numerical differentiation are applied to detect the ionospheric temporal gradients. Time-step and Stationpair methods are used to detect the spatial gradients. Ionospheric gradients at GNT and MPM stations for the month of January 2015 have been discussed. The gradients are found to have occurred mostly between 2000 and 2200 hrs LT. The maximum value of ionospheric gradient velocity is 473.25 ms-1. The S4 value is above 0.8 and the phase scintillation value is above 0.7 radians.

Madhavi Latha D.,Koneru Lakshmaiah University | Madhav B.T.P.,Koneru Lakshmaiah University | Datta Prasad P.V.,Hindu College | Pisipati V.G.K.M.,Koneru Lakshmaiah University
Journal of Molecular Liquids | Year: 2010

Different thermodynamic parameters such as Sharma parameter (S o), Huggins parameter (F), reduced volume (V∼), reduced compressibility (V∼ C1) etc., are estimated from the volume expansion coefficient (α) for N-(p-n-alkoxybenzylidene)-p-n- pentyloxy aniline (nO.O5) compounds in isotropic and liquid crystalline phases. The parameters like intermolecular free length (Lf) and molecular radius (mr) are also computed from density and refractive index for these nO.O5 compounds. The results are discussed in the light of these parameter variations with temperature in a particular phase, in a liquid crystal molecule and in a homologous series. The thermodynamic parameter So exhibits a constant characteristic value (1.15 ± 0.05) in all the compounds like other reported liquid crystalline compounds and liquids. The variation of other thermodynamic parameters in all the phases of these compounds with temperature is discussed in the light the body of the data available. © 2010 Elsevier B.V. All rights reserved.

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